This is not a natural position. Crested geckos doe sort of roll back the tips of their toes during natural movements, when they 'unstick' themselves as they walk. But the claw won't come in contact with the top or bottom of the foot (from the description I am assuming the claw is in the top of the foot, not just resting against the sole of the foot when relaxed).
I suggest taking him to a vet...the toe may be broken or some other reason causing it to take an unnatural position. It could also be a birth defect that has gone unnoticed. If you have a good clear picture, it may be easier to tell if its a break, natural or birth defect.
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PHLdyPayne
Forum Princess